Equipment for semi-conductor manufacturing includes writers and inspection equipment for producing images on reticles and large area masks, for direct writing of patterns for chips, and for inspection of patterned work pieces. Over time, chips have become increasingly complex and dense, as processors, memory circuits and other semi-conductors have gained greater capacity. Memory circuits, in particular, and all circuits with small feature sizes, in general, have become denser. Patterns for these circuits have become even more complex than the circuits, as optical proximity and laser proximity correction features have been added to the patterns. The equipment and writing strategies have become increasingly sophisticated, in response to requirements for smaller features on chips and tighter critical dimensions. One description of equipment and writing strategies developed years ago to meet the needs for semi-conductor manufacturing equipment is found in U.S. Pat. No. 5,533,170 issued to Teitzel et al. on Jul. 2, 1996.
Another challenge for manufacturers is to compensate for variations in process chemistries, such as variations in responsiveness of resists to exposing radiations. Variations are found in the response of different types and even batches of resists to exposure. Resists sometimes respond differently near the edges and in the corners of coated work pieces.
As manufacturers strive to keep pace with the Moore's law, there is a continuing need for writers and inspection equipment that can process large volumes of geometric figures and produce precise patterns on work pieces. There is a corollary need for techniques, methods and equipments that compensate for variations in resist and other process variables, while producing the needed precise patterns.